A Level Biology Revision (Year 13) "The Action Potential and the All-or-Nothing Principle" @Freesciencelessons

Uploaded January 2024 | Updated September 2026, 1 day ago

In this video, we look at the action potential and the all-or-nothing principle. First we explore the events that take place during the action potential. We explore how voltage-gated ion channels operate and how the axon membrane undergoes depolarisation, repolarisation and hyperpolarisation. We then explore what is meant by the all-or-nothing principle.

Resting potential: youtu.be/1FsLLtwU6CY

Receptors: youtu.be/7LSB3wtO1wc

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$GCSE Chemistry Revision Fractional Distillation Find your 9s with PLUS. Click the link to try for free https://www.freesciencelessons.co.uk/modules/gcse-chemistry-1-triple/ Teachers, to get PLUS for your school, email schools@freesciencelessons.co.uk In this video, we look at fractional distillation. First, I explain how fractional distillation is used to separate a mixture of liquids each with a different boiling point. We then look at the apparatus used to carry out fractional distillation, including the role of the fractionating column and the condenser. We explore how to deal with liquids which have similar boiling points and why the apparatus shown is not used for separating crude oil. This video is based on the AQA spec. This video may be appropriate for iGCSE / O Level Chemistry. Please consult your specification. The Amazon link above is an affiliate link. This provides a small commission which helps to support freesciencelessons. The cost remains the same to you. If you prefer not to use this, you can search Amazon for the Freesciencelessons workbooks.$